In 2016 they added an "enhancement" that when you pick on the dimension text while sketching, it pops up the dialog to change the dimension number. Is there a way to turn this OFF so that it behaves like it has in all the previous releases. Just another one of their "useful" enhancements in 2016 that kills any speed enhancements they may have added.

Single click the dimension text "Ø 1.000" and this is the result by default in 2016:

This is different from the expected behavior that occurs in 2015 and earlier versions. Disabling the new Instant2D functionality in 2016 will result in the same expected behavior from previous versions. Single clicking the dimension will now result like this:

The dimension is now selected (highlighted) without opening an unexpected edit box.

I personally like the new user interface with its updated look, but I certainly understand your concern about lack of contrast in the icons. you could try changing the interface brightness. It's not an exact fix, but it might help some.